Transformer mounting



Jan. 7, 1958 E. H. BLADH momma uounzrmc 1mm Airil 27. 1953 IN VEN TOR. ATTOENEY5.

i to rnreo. htates 2,819,331 TRANSFORM R MOUNTING Application April 27, 1953, Serial No. 351,247 4 Claims. (Cl. 174-52) This invention relates to transformers of the type employed for energizing household bells, chimes, and similar low voltage apparatus. The invention is directed particularly to an improved construction by means of which a transformer may be mounted conveniently and easily upon an electrical outlet or junction box where an electrical connection may be made to the higher voltage supply lines.

The conventional low voltage transformer consists of primary and secondary windings which embrace a magnetic core, and a housing, usually of sheet metal, which encloses all of these elements. The primary winding of the transformer is energized from a relatively high voltage source, such as the usual house distribution circuit which carries 110-120 alternating current, and the secondary winding is electrically interconnected with low voltage apparatus, such as a bell, buzzer, chime, or the like, with a switch being installed in the secondary circuit for signal or control purposes.

The voltage in the output circuit of the transformer is so low that there is no great danger of fire being caused even if it is short-circuited; hence, the output circuit may be installed with the use of ordinary bell wire or the like. However, a great fire hazard exists unless proper installation precautions are observed with respect to the high voltage distribution system and any connections which are made to it. It is common practice, therefore, to utilize a fireproof sheet metal outlet or junction box wherein the wire connections may be properly housed and insulated so as to avoid short-circuiting and also to confine and suppress any flame or smoldering that might attend short-circuiting if it occurs. The usual outlet or junction box is provided with one or more knockout plugs in its wall surfaces through which electrical wires may be passed.

The principal objective of this invention has been to provide a transformer having mounting means associated with one of its faces which enable the transformer to be mounted directly upon a Wall of an outlet box in order to eliminate the need of mounting the transformer separately from the outlet box.

A further objective of this invention has been to provide a simple and inexpensive mounting device for removably associating a transformer with an outlet box at a knockout hole thereof, through which the input leads of the transformer may also extend for interconnection with the supply circuit interiorly of the box. Other objectives of this invention appear in the following detailed description of the drawing in which a typical embodiment of the invention is illustrated.

In the drawing:

Figure 1 is a somewhat diagrammatic view showing a typical outlet box having a transformer associated with it in accordance with this invention;

Figure 2 is an enlarged sectional view showing the mounting means of a transformer of the present invention in position securing the transformer to an outlet box;

Figure 3 is an elevation of the mounting means of the present invention;

Figure 4 is a sectional view taken on the line 4-4 of Figure 2; and

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2,819,331 Ratented Jan. 7, 1958 ice Figure 5 is a perspective view showing a typical transformer equipped with mounting means in accordance with this invention.

The transformer with which the mounting means of the present invention may be associated may be of any suitable external shape and interior construction. The typical transformer which is illustrated in the drawings comprises a magnetic core 1 having cap pieces 2 at its opposite faces which house the primary and secondary windings that are associated with the core. Since the interior construction of the transformer forms no part of the present invention, these details are not shown in the drawings, but it is appropriate to note that the transformer is provided with output leads or terminals 3-3 and input leads or terminals 44 The output or low voltage terminals may be located at any place on the transformer, but, for reasons subsequently explained, the input terminals in the preferred construction pass through suitable openings in the facial portion of one of the housing cap members 2.

The housing caps 2 are provided with apertured foot members 5 in the usual manner to facilitate the mounting of the transformer upon a joist or stud by means of screws or nails. However, in accordance with the present invention, a transformer mounting bracket, indicated generally at 6, also is associated with the transformer to facilitate its attachment directly to a junction box at a knockout hole thereof.

The bracket 6 in the preferred construction is associated with the face portion of the end cap 2 through which the input leads project, and it preferably is mounted in between the input leads. The bracket may be in the form of a bent metal strip 7 which is riveted to the end cap 2, by means of rivets 8. In a typical transformer construction, the end caps or housing are lined with an insulating paper, for insulation purposes, and, in the construction shown, the rivets 8, extending through the cap wall and associated insulation 9, are spun over an additional block 10 which may also be of insulation material, such as fiberboard. However, in place of the construction shown, any suitable fastening means may be utilized.

One end of the strip 7 is bent outwardly so as to provide a clip as at 11. The opposite end is also bent outwardly, preferably in an angular direction, as at 12, so that the legs 11 and 12 are divergent with respect to one another. A fastening screw 14 is threaded through a tapped hole in the leg 12 of the bracket, the screw preferably having a cup point 15 and being disposed on an axis generally intersecting the inner edgewise portion of a knockout hole when the bracket is positioned as in Figure 2.

Bracket 6 is of such overall length that the distance across the extremities of the legs 11 and 12 in a direction parallel to the plane of the face of the cap 2 approximates or is slightly greater than the diameter of a conventional hole in a knockout box, which is approximately one inch. Leg 11 of the bracket cooperates with the face of the housing or cap 2 to provide a notch or recess therewith, indicated at 17, by means of which the wall portion of an outlet box adjacent the knockout hole may be straddled or received upon insertion of the bracket through the hole. This is shown in Figure 2; the outlet box, indicated generally at 18, is provided with a knockout hole 19, and the wall portion of the outlet box marginally adjacent the knockout hole is straddled by the face of the cap 2 on the outside and by the inner face of the leg 11 on the inside of the outlet box.

Leg 12 of the bracket 6 is angulated so as to position or direct the cup point 15 of the screw 14 into engagement with the metal of the outlet box at the inner edge of the knockout hole opposite the point or points of engagement of leg 11 therewith. Therefore, by tightening the screw 14 the cup point, bearing upon the inner edge of the knockout hole, wedges the bracket piece in place and at the same time draws the face of the cap 2 of the transformer firmly against the outer face of the outlet box around the knockout hole thereof.

In causing the leg 11 of the bracket to be wedged against the metal of the outlet box at one side of the knockout hole, a firm frictional connection is established, and, if sufficient pressure is exerted on the screw, the edgewise portions of the leg 11 will be caused to actually bite into or dent the edge metal of the knockout hole as at points Ell-- thereof. At the same time, the cup point on the screw 14 bites into or dents the metal at the opposite side of the knockout hole so that a nonrotatable connection of the transformer and the outlet box is established. The transformer conveniently may be demounted at any time merely by loosening the screw 14 and shifting it relative to the knockout hole sufficiently to permit the leg 12 to clear the hole and be withdrawn through it.

The typical outlet box is of rectangular or octagonal configuration, With an open face. Knockout holes are located in the side walls and a cap piece is provided to cover the open face after the electrical connections have been made within the box. An important feature of the present invention resides in the fact that the slotted head of the fastening screw of the transformer mounting bracket is conveniently accessible through the open face of the outlet box, as distinguished from past mounting devices wherein the side walls of the outlet box obstructed access to the head of a fastening screw. For example, in a typical installation of the present apparatus, the outlet box is nailed or screwed into place at a point where it is to be located in a building, the transformer is placed against the outside of the outlet box with the mounting bracket extending through the selected knockout hole of the box, and the transformer is then rotated so as to bring the screw head to a position where it is conveniently accessible, after which the screw is tightened, thereby mounting the transformer firmly and non-rotatably upon the box.

Having described my invention, I claim:

1. A transformer having a housing providing a facial portion and having electrical input members located on said facial portion in spaced relationship to one another, and means for mounting the said transformer upon an outlet box at a knockout hole thereof, comprising, leg members disposed generally in between the said electrical input means, the said leg members extending angularly from the plane of the said transformer facial portion in generally opposite directions and being dimensioned across their extremities for disposition through the knockout hole of an outlet box so that endwise portions of the legs may project through the hole and reside interiorly of the box while the said transformer facial portion abuts the exterior thereof, one of said leg members providing a clip for engaging the outlet box wall edge delineated by said knockout hole, and the other of the legs having a Wedging screw threaded transversely therethrough in position for engagement of its end with a substantially opposed wall edge of the knockout hole, the first of said legs having a sharp edge adapted to indent the edge of the knockout hole upon being wedged into engagement therewith by said screw, and thereby mount the transformer non-rotatively upon the outlet box.

2. A transformer having a housing providing a facial portion and having electrical input members located on said facial portion in spaced relationship to one another, and means for mounting the said transformer upon an outlet box at a knockout hole thereof, comprising, leg members disposed generally in between the said electrical input means, the said leg members extending angularly from the plane of said transformer facial portion til in generally opposite directions and being dimensioned across their extremities for disposition through the hole of a knockout box so that endwise portions of the legs may project through the hole and reside interiorly of the box while the said transformer facial portion abuts the exterior thereof, one of said leg members providing a clip for engaging the outlet box wall edge delineated by said knockout hole, and the other of the legs having a wedging screw threaded therethrough in position endwisely to engage a substantially opposed wall edge of the knockout hole, the first of said legs having a sharp edge adapted to indent the edge of the knockout hole upon being wedged into engagement therewith by said screw, and thereby mount the transformer non-rotatively upon the outlet box, and the said screw having a cupped point for indenting the edge of the knockout hole under pressure engagement therewith.

3. The combination of a transformer having a housing providing a facial portion and having electrical input members located on said facial portion in spaced relationship to one another, and means for mounting the said transformer upon an outlet box at a knockout hole thereof, comprising a strip of metal disposed generally in between the said electrical input means and fastened to said facial portion of said housing, said strip of metal having its endwise portions bent angularly in respectively opposite directions from the plane of the said facial portion so as to constitute leg members, the said leg members being dimensioned across their extremities for disposition through the hole of a knockout box so that endwise portions of the leg members may project through the hole and reside interiorly of the box, one of said leg members and the said facial portion adjacent thereto being adapted to straddle the inner edge of the knockout hole, the other of the legs having a wedging screw threaded transversely therethrough for engagement with a substantially opposite inner edgewise portion of a knockout hole, and means carried by at least one of said legs for indenting the edge of the knockout hole under pressure engagement therewith to prevent rotation of the transformer relative to the outlet box.

4. A transformer having a housing providing a facial portion and having electrical input members extending through said facial portion, and means for mounting the transformer upon an outlet box at a knockout hole thereof, said means comprising leg members disposed adjacent the said electrical input members, the said leg members respectively extending at acute angles from the plane of the said transformer housing facial portion in generally opposite directions and being dimenisoned across their extremities for disposition through the knockout hole of an oulet box so that the endwise portions of the legs and the adjacent electrical input members may project through the hole and reside interiorly of the box while the said transformer housing facial portion abuts the exterior thereof, one of said leg members and the portion of the said transformer housing facial portion adjacent thereto being adapted to straddle the outlet box wall edge delineated by said knockout hole and the other of the legs having a wedging screw threaded transversely therethrough for engagement of its end with a substantially opposite portion of the wall edge of the knockout hole, whereby pressure engagement of the screw with the one wall edge portion of the knockout hole forces the other leg portion firmly into engagement with an opposed wall edge portion of the knockout hole and draws the facial portion of the housing into tight facial engagement with the outlet box at areas around said knockout hole.

Bissell Apr. 24, 1917 Goddard -r---- Dec. 30, 1947 

